With the diversification of network usage, the introduction of a communication system having a form for collecting data through a communication between wireless devices has been advanced, in which multiple wireless devices are accommodated under a gateway to configure a wireless multi-hop network. However, there is a case in which even if a wireless device is installed on a site, the wireless device cannot communicate with another wireless device due to radio shielding caused by an obstacle or the like, or there is a case in which even if the communication is enabled, a communication quality is poor and a desired communication requirement cannot be achieved. In such a case, in order to secure a communication connection and stabilize the communication quality, an engineering work is required to add a wireless device as a repeater at an appropriate location.
As a prior art for determining an installation location of the repeater, there is a technique (Patent Literature 1) that detects wireless devices connectable with one hop in each predetermined installation location candidates of a repeater, and determines the good installation location of an repeater from the candidates based on detection results (Patent Literature 1). In the above prior art, a location connectable with one hop to both of a wireless device having a communication path leading to a gateway and a wireless device which is in an isolated state is selected from the installation location candidates and employed as an actual installation location of a repeater. The above processing is repeated until there are no isolated wireless devices, thereby being capable of determining the placement of the repeater which obtains a communication route through which all of desired wireless devices reach the gateway.